[Samba] locking in samba

[Demchenko Yevheniy]

Hello! I've got into problems with simultaneous access to files on samba 
server. Two (or more) people from different computers may open the same file 
and may independently change it (with openoffice, for example). Certainly, 
this is not the expected behavior. If the file is shared on windows machine, 
when the first user opens it, he gots RW permission, while the next one(s) 
may open this file only as read-only. 
Tried on Samba3.0 alpha22, Samba3.0beta1 and Samba3.0rc1.
blocking locks, posix locking and locking are set to yes in smb.conf, 'force 
user' is not set.
smbstatus says "Denymode DENY_NONE, oplocks NONE" on every connection to the 
mentioned file.
I've tried to switch on/off oplocks, level2 oplocks, kernel oplocks, strict 
locking, - nothing helps.
What am i missing?
Thanks.